For the imp 'hero', leave the DK on the other side of the village, and approach the imp with just your other character. That should avoid the problem.
The BF dungeons are randomly generated, and can occasionally contain disconnected sections or entrances that you can not get to. It is possible to get a summoning doll to appear through a wall, and then use the teleporter pyramids to get through (
armory trick in act 1). Alternately, you use the procedure in the topic
Teleporting anywhere (via hex editor). It may not be worth the hassle, though, just for BF quests (I skipped the BF dungeons entirely, and only visited for the merchants).
The solutions to the quests are randomly distributed on the third levels of the dungeons, so it is possible that any particular dungeon may not none, one or multiple quest solutions.
